docs: def _checkSetpointValue( setpointvalue, maxvalue ):   
      """Check that the given setpointvalue is valid.
      
      Args:
          * setpointvalue (numerical): The setpoint value to be checked. Must be positive.
          * maxvalue (numerical): Upper limit for setpoint value. Must be positive.
          
      Raises:
          TypeError, ValueError
      
      """
      if maxvalue is None:
          raise TypeError('The maxvalue (for the setpoint) must not be None!')
      minimalmodbus._checkNumerical(setpointvalue, minvalue=0, maxvalue=maxvalue, description='setpoint value')